1. Field of the Invention
This invention relates to a process for preparing reinforced plastic plates. More particularly, this invention relates to a process for preparing reinforced plastic plates made of thermosetting resin in which the heat-curing of the resin is conducted under specific conditions such that the plate does not undergo major warpage after molding.
2. Description of the Prior Art
Because of their excellent characteristics such as high corrosion resistance, light weight and high heat resistance, plates made of reinforced plastics have heretofore been used as collecting electrodes of electrostatic precitators and the like. However, in the case of large-size flat plates, the prevention of warping of the plates after they are molded has been an important problem, and various methods for preventing warping have been proposed. For example, there are generally employed a method in which a molded plate is heat-cured while it is held between two flat plates or a method in which there is used a resin of low shrinkability formed by incorporating a filler into the resin. However, these methods are unsatisfactory. More specifically, the former method is suitable for molding relatively small plates, but in the case of large plates, for example, a plate having length and width dimensions each of more than 1 m, the occurrence of warping in the central portion of the plate cannot be prevented. In the latter method, the corrosion resistance of the plate is degraded by incorporation of the filler and satisfactory effects cannot be obtained.